Exposed: Is it possible create an entity class from a table with a composite primary key?

[jorginius]

It seems the API forces the IdTable derived objects have got only one key column. Is there any equivalent to the JPA's EmbeddedId and IdClass annotations?

[Tapac]

Hi, @jorginius .
It's not possible at the moment, but I hope we can fix it in a while.
Do you have any experience with EmbeddedId or IdClass approach? Or maybe you can share your vision how it might be implemented to be mostly useful?

[jorginius]

Hi, @Tapac .

I commented about the EmbeededId (and Embeddable) annotation because I think it could be the less disruptive approach (one object key, one parameter), but I'm not sure if mimicking JPA is the right way on this point:

@Embeddable
public class UserToRoleKey {
   @Column(nullable = false)
   private String code;
   @Column(nullable = false)
   private String username;
   // ...
}

@Entity
public class UserToRole {
    @EmbeddedId
    private UserToRoleKey key;
    // ...
}

// ...
UserToRoleKey key = new UserToRoleKey();
key.setCode("USER");
key.setUsername("test);
entityManager.find(UserToRole.class, key);

"Raw" Table objects can hold a composite key easily:

internal object UsersToRoles : Table("users_roles") {
    val code = reference("code", Roles.code).primaryKey()
    val username = reference("username", Users.username).primaryKey()
}

Perhaps the ideal API :-) has a EntityClass which works with Table objects (creating EntityId from primaryId fields automatically) or IdTable is deprecated/superseded by the "vanilla" Table, i don't know.

[kamyar1979]

It is my only problem in current project! Please lead me with a workaround at least!

[Tapac]

@kamyar1979 , sad, but there is not workaround atm, because entityId is a hardly coupled with a single column instance. We have uncompleted refactoring with this feature support, but it requires a lot of testing before release, so we can't give any ETA :(

[kamyar1979]

Sorry! I have to return to old Hibernate for now!

[OleksandrSamsonov]

Need this feature as well :(

[MigiKun]

Any news?

[rnett]

A very ugly and <8 bit int-specific work around I've been using:

object dgmtypeeffects: IntIdTable(columnName = "typeID\" << 8 | \"effectID") {
    val typeID = integer("typeID").primaryKey()
    val effectID = integer("effectID").primaryKey()
    val isDefault = bool("isDefault")
    val effect = reference("effectID", dgmeffects)
    val type = reference("typeID", invtypes)

    fun idFromPKs(typeID: Int, effectID: Int): Int {
        return typeID shl 8 or effectID
    }

    fun findFromPKs(typeID: Int, effectID: Int): dgmtypeeffect? {
        return dgmtypeeffect.findById(idFromPKs(typeID, effectID))
    }

}

class dgmtypeeffect(id: EntityID<Int>): IntEntity(id) {
    companion object: IntEntityClass<dgmtypeeffect>(dgmtypeeffects)

    var typeID by dgmtypeeffects.typeID
    var effectID by dgmtypeeffects.effectID
    var isDefault by dgmtypeeffects.isDefault
    val effect by dgmeffect referencedOn dgmtypeeffects.effect
    val type by invtype referencedOn dgmtypeeffects.type

}

findByPKs returns the correct object, and accessing these by references in other tables works, I can't say more than that.

The shift could be adjusted, and more values could be added.

[jcflorezr]

seems there is a solution here: https://github.com/JetBrains/Exposed/issues/239

[Hc747]

Have there been any updates on this?

[Tapac]

@Hc747, not yet.

[DRSchlaubi]

This issue was created 4 years ago, how is this not fixed yet?

[kimble]

This issue was created 4 years ago, how is this not fixed yet?

You should ask for your money back

[brunoazevedomendonca]

I believe that I found a solution:
https://stackoverflow.com/questions/57633755/kotlin-exposed-entity-for-table-with-no-identity-column

[PedroD]

@Tapac is there any README about this on-going feature that the community can read and try to contribute?

[downloadpizza]

Bumping because this is ridicolous, I just made an IntIdTable now without using the Id ever.

[Displee]

Bump :)

[akamuza]

5 years later we still need it. Really )

[simonnepomuk]

Bump :)